feat: add Tests/RestServiceExceptions

[TimothyMakkison]

Added tests to verify that RestMethodInfo throws an exception when invalid interfaces are initialized through RestService.For.

This duplicates tests found in Refit.Tests/RequestBuilder however these will have to deleted if I get round to removing RequestBuilder and all corresponding runtime logic

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.28%. Comparing base (6ebeda5) to head (75442d9).
Report is 140 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1886      +/-   ##
==========================================
- Coverage   87.73%   84.28%   -3.45%     
==========================================
  Files          33       36       +3     
  Lines        2348     2476     +128     
  Branches      294      347      +53     
==========================================
+ Hits         2060     2087      +27     
- Misses        208      310     +102     
+ Partials       80       79       -1     

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